This invention relates to capacitors and to methods of forming capacitors.
Typical capacitors comprise a pair of conductive electrodes spaced apart by intervening capacitor dielectric material. As integrated circuitry becomes denser and as individual electronic components such as capacitors get smaller, integrated circuitry fabricators face the challenge of developing capacitor constructions and materials which achieve desired capacitance despite the decreasing size. Example materials under consideration for capacitor dielectric layers include titanates and tantalum pentoxide. These and other capacitor dielectric layer materials can occur in crystalline and in amorphous phases.
It is generally known that the capacitance of dielectric materials such as these can, at least initially, be increased from their as-deposited form by annealing. Such annealing can promote crystallization, re-crystallization or crystal realignment which can facilitate increase in capacitance and reduction in current leakage through the material. However, such annealing can also cause single crystals to be formed in the dielectric layer which in essence extend entirely through the dielectric layer between the layer""s opposing surfaces. Annealing or crystal formation to this degree can undesirably have the effect of increasing current leakage. This is primarily due to continuous paths being provided by the continuous grain boundaries for current leakage from one side of the layer to the other. It would be desirable to improve upon these adverse characteristics of capacitor dielectric layer materials.
The invention in one aspect includes methods of forming capacitors and to capacitor constructions. In one implementation, a method of forming a capacitor includes forming a first capacitor electrode. A first layer of a first capacitor dielectric material is formed over the first capacitor electrode. A second layer of the first capacitor dielectric material is formed on the first layer. A second capacitor electrode is formed over the second layer of the first capacitor dielectric material. In accordance with another implementation, the first layer comprises a first titanate compound comprising capacitor dielectric material and the second layer comprises a different second titanate compound comprising capacitor dielectric material. A capacitor in accordance with an implementation of the invention includes a pair of capacitor electrodes having capacitor dielectric material therebetween comprising a composite of two immediately juxtaposed and contacting, yet discrete, layers of the same capacitor dielectric material. A capacitor in accordance with another implementation includes a pair of capacitor electrodes having capacitor dielectric material therebetween comprising a composite of two immediately juxtaposed and contacting, yet discrete, layers of two different capacitor dielectric materials, said two capacitor dielectric materials including two different titanate compounds. A capacitor in accordance with still another implementation includes a pair of capacitor electrodes having capacitor dielectric material therebetween comprising a composite of two immediately juxtaposed and contacting, yet discrete, layers of two different capacitor dielectric materials, one of the two different materials comprising a titanate compound and the other comprising Ta2O5.